Electronic bilge pump switch

davel

davel

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My boat has a relatively small, narrow bilge. I want to fit a water detection switch (to activate a bilge pump) but a convetional float switch won't fit. Ideally I'd like an electronic switch with two detection levels (one for activation and one for switch off). I seem to remember reading an article about such a switch (might even have been home grown).

Does tghis ring a bell with anyone? Could you point me in the right direction?
 
[ QUOTE ]
Install a flexible pipe with a washing machine pressure-activated switch on the top end.

[/ QUOTE ]

What sort of depth are you talking about before the bilge switch activates? ... My experiments with washing-machine sensors suggest they are far too crude to detect a few inches of water?

Electronic sensors based on conductivity should work, but have yet to see any satisfactory reports.

If space is really a problem, has original poster considered vertical action float switches? .... more specialist and therefore probably more expensive.

Vic
 
A friend had a home made electronic bilge switch in his bioat when he bought it. It is nowremoved more because all the wiring had corroded and a mechanical bilge switch was available.
Incidentally the simple wiring to the mechanical switch corroded away within weeks because the +ve wire was lying in the unpumpable water and electrolysis quickly dissolved the crimp.

The electronic switch has advantage that electrodes can be extended as sensors to any level you want.

i don't have a circuit but simplistically a CMOS gate chip like 4000 4001 or 4011 has the gate biassed to +ve voltage through a 1 meg ohm resistor. The gate is also connected to an electrode like a bolt head at the appropriate level. The other electrode is -ve or earth.

When the sea water covers both elecrodes the low resistance effectively shorts the input to ground because the high resistance can't maintain the +ve bias which turns on the gate. The +ve output from the gate, switches on a transistor to activate the pump.

To have a different off level you need to switch on a flip flop pair of gates which stays on until at a lower level the absence of seawater covering electrodes will flip the gate back to off.

Alternatively you can have just one electrode pair but have a large capacitor on the input such that onece on it tends to stay on for some seconds before going off to stop the short term operation with waves etc.

Electronically it is fairly simple but in practice it is difficult to prduce a device which will resist corrosion etc. So you may be better to persue a commercial bilge pump switch. PM me if you want more help. olewill
 
We have electronically controlled rule pumps ... the pump checks for water every 2 to 5 minutes and then if resistance is felt, the pump is activated.


No problems with switches and easily corroded wiring in the bilges!
 
I have one of the 'twin sensor' models in a deep builge. Only works WELL, if water not contaminated with any engine oil and/or grey water.

Don't know what make it is - not had it out yet. It's orange - so is the 1500 pump, if that's any help!? Sorry!
 
Look in the RS catalogue. There are some narrow mechanical (reed) switches and electronic ones also. 477-4676 is an electo-optical device that relies on total internal reflection. I have one at the top of each fuel tank to alarm when full (to stop overfilling - and NO I can't see from the side as they are beolw the sole!). Cost around £14.

I also have three mounted on a pole inside my domestic heating oil tank indicating three quarters, one quarter and "It's going to get cold soon".
 
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